Spark-plug.



E'. HARTER. SPARK PLUG.

APPLIGATON FILED JULY 26, 1912.

Patented Mar. 1'?, 1914.

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SPARK-PLUG.

Specification of Letters Patent.

atout-ed Mar. 1?, 191ML.

Application filed July 26, 1912. Serial No. 711,682.

To a?! whom 'it ra n.1/ concern l Be it known that. l. Fnxxlt ll. llAirrnn. a citizen of thel United States, residing' at Olympia, in the county ot Thurston. State et' lVashington. have invented certain new and useful lmprovements in Sparkdlngs; and l do hereby declare the following-to be a liull, clear, and exact.description ot' the invention, such as will enable'others skilled in the art to which rit appertains to nnuike and ilse the same.

This invention relates'to .spark plugs and has for an object' to improve this class otE devices by the provisioinot' a novel divigled electrode adapt-ed to vproduce a multiple spark gap.

'A further object. ol' the invention is to provide a novel insulator tor supportingr the divided electrode.

lVith the above objects in view the invention consists of certain novel details of construction and combination ot parts hereinal'ter fully described and claimed. it heine' understood Athat various nunliticatious ma)1 he, nfade in the minor detailsl ol' construction within the scope of the appended claim.

ln the accompanyhre' drawing forming part of this specitifatlon: lfigure l is a front elevation ot' the spark plug. ["ig. SZ is a longitudinal Sectional view through the, spark plug'. ltig'. il is a bottom plan view ot' the spark plug'. .Fig l; is a cross sect ional view taken on the line lf-t- Fig'. 2. ltile'. 5 is a cross sectlional view taken on the line ti-5 Fig. L). Fig. t is a detail inrspectivc view ot' oneinemher ol the divided electr-tule.

Referring' now to the drawing;t in which like characters ot' reference designate similar parts, the spark plug is shown to comprise a central cylindrical core l() preterablly vt'ormed ot" porcelain. 'lhe core is provided with an axial opening' through which a terminal Ll is engaged. 'lhe core is At'urther provided at the lower end with a imiformely enlarged shoulder l2. metallic externally thraded attaching' hase l. bars at the lower end against; this shoulder and is provided with a tapered bore which receives the core and into which is threaded a lock nut 14. A wedge ring' l5 lits in an annular groove lt li'ormcd in the core, the nipple 17 otl thel lock nut being tapered to a thin edge and beinzer interposed between the wedge and base to frietionallv lock -the core and base together. i

The divided terminal consists of a circular series ot' substantially T-sl1aped metallic pins 1S the shanks of which are embedded in the bottom Ytace of.' the porcelain door, and the heads ot which are arcuate in ontline and are exposed in their entireties considerahlv below the bot-tom :tace et the core. 'lhe shank of one of the pins is extended as shown at llt and is terminallyY connected to themetallic attaching base 18.. The heads ot' the pins; are spaced slightly apart. with resultant spark gaps 520 existingjr therebe tween. 'lhe inner terminal ll is provided with a laterally directed spark point which is directed toward and is slieglitliy spaced from the head ot one ol the pins as shown at 21. llach time an electric circuit is eomplet-ed through the terminals ll and 19. a plurality ot.' spa rksl will be produced in the spark gaps existing' between the separated heads ot' the pins 18, and the resnitant circalar series ot sparks will positively insure the ignition of the explosive mixture in the engine cylinder.

ln a spark plug. a metallic base, a core ot insulating' material in said base, a straight central electrode in said core, having an exposed straight lower end terminating in a laterally directed spark point. and a second Aelectrode comprisingr a circular series of T- shaped metallic pins concentricallyv arranged with respect to thel exposed straight lower end of said central electrode and having' parallel Shanks extending;A longitinlinally in said core and having' arcuate exposed heads spaced apartwith resultant spark `raps therebetween. the shank ot' one ot said pins heing longitudinally prolonged and terinitially connected to said baseysaid spark point: extending' toward but not contacting' with one ot' said heads.

ln testimony whereof. l atlix my signature. in presence ot'two witnesses.

' FRANK l". llikll'llll.

lV it nes-ses:

J. 'l`. Oris, (l. I". Winnno. 

